(Low numbered receiver are those with serial numbers below 800,000 made at Springfield Armory, and below 286,506 made at Rock Island Arsenal.) Some have stated emphatically no rifle with a low numbered receiver should ever be fired under any circumstance because of the risk of serious injury or death, but that high numbered receivers are perfectly safe._

CZguy

September 2, 2004, 04:57 PM

Thank you both very much!

jobu07

September 2, 2004, 05:20 PM

Does that have something to do with modern ammo being hotter than ammo of the time? Or are the low numbered receivers just not safe to shoot period?

Jim Watson

September 2, 2004, 05:44 PM

The "low numbered" receivers are made out of mild steel, single step heat treated and casehardened for surface wear in the same way as the .30-40 Krag which operated at about 20% lower pressure.

This is strong enough, IF done just right, IF the ammo is to spec.
But if you have a hot load or a piece of bad brass that blows the casehead and if the hardening, then done by eyeball temperature control, was a little too hard and therefore brittle, the gun fragments.

Hatcher documents 138 guns blown up out of over a million produced. Most with greased ammo (They had their reasons.), 8mm ammo crammed into a '06 chamber, WW I contract ammo with low grade brass, or firing with a barrel obstruction. Most.
But you can break a brittle low numer action by dropping it on a concrete floor or hitting it with a hammer. A non-brittle low number action will wear out several barrels. But how do you know which you have? I have shot a low number rifle and lived over it, but I would not make a regular practice of it.

Later '03s were mild steel but double heat treated for high strength and hardness. Still later they went to nickel steel, then in WW II to manganese steel.